\ \ jxCAi/  / sn  History  Survey  of  Minnesota 

I On  way  MacMillan,  State  Botanist 


/ 


A 


Minnesota 
Botanical  Studies 


i 


Contents 

XVI.  On  a new  registering-  balance,  Alex.  P.  Anderson 
XVII.  On  a new  electrical  auxanometer  and  continuous 
recorder,  W.  D.  Frost 

XVTII.  Titles  of  literature  concerning  the  fixation  of  free 
nitrogen  by  plants,  D.  T.  MacDougal 

"W\i,  ' 

wei 


U 


f 


Bulletin  No.  9 

Part  IV  - - Sept.  27, 1894 

With  four  plates. 


177 

181 

188 


h 


MINNEAPOLIS,  MINN. 
HARRISON  & SMITH,  STATE  PRINTERS 
1894 


# 


framing  anb  f akr. 

LIBRARY 

Universityof  Illinois. 

§ CLASS.  BOOK. 

| fe’bvsA  nv^ 


« 


VOLUME). 


Accession  No. 


XYI.  ON  A NEW  REGISTEBING  BALANCE. 

Alex.  P.  Anderson. 


In  the  course  of  certain  experiments  on  transpiration  lately 
conducted  in  the  laboratories  for  plant  physiology  of  the 
University  of  Minnesota  it  became  apparent  that  to  .ascertain 
the  rate  of  transpiration  for  some  length  of  time  some  self 
registering  mechanism  that  could  be  used  to  record  the  increase 
in  the  weight  of  the  absorber  was  necessary.  With  such  an 
appliance  the  periodicity  (if  any)  in  transpiration  could  be 
determined,  and  a true  transpiration  curve  plotted.  After 
repeated  trials  and  alterations,  such  a registering  balance  has 
been  designed  consisting  essentially  of  a balance,  one  arm  of 
the  beam  of  which  is  lowered  by  the  increase  in  weight  of  the 
calcium  chloride  absorber. 

As  this  arm  is  lowered  a circuit  is  closed  and  an  electro- 
magnetic mechanism  releases  a weight  which  falls  on  the  other 
arm  of  the  scale  beam,  or  rather  into  its  scale  pan.  Thus  the 
scale  is  balanced  automatically,  after  an  increase  equal  to  the 
weight  used  has  taken  place.  At  the  same  instant  that  the 
weight  is  released  it  is  recorded  on  the  registering  cylinder  of 
the  recorder,  which  can  be  at  any  distance  from  the 
balance  itself.  The  scale  and  balancing  mechanism  are 
enclosed  in  a case  which  entirely  protects  the  whole  from  fall- 
ing moisture. 

The  following  detailed  description  will  serve  to  illustrate  the 
action:  The  weighing  apparatus  consists  of  a platform  scale 

made  especially  for  the  purpose,  and  to  fit  the  registering 
mechanism.  This  scale  is  sensitive  to  one-fifteenth  of  a gram, 
with  a capacity  of  five  kilograms.  It  has  abeam  eleven  inches 
long,  the  supports  of  which  are  screwed  to  an  iron  plate  in  the 
bottom  of  the  case,  thus  making  the  scale  and  case  practically 
one  and  both  can  be  leveled  and  adjusted  together.  The  brass 
scale  pans  are  seven  inches  in  diameter  and  are  carried  by 
brass  supports,  attached  to  the  arms  of  the  scale  beam.  The 
scale  bearings  are  of  diamond  steel. 


178 


MINNESOTA  BOTANICAL  STUDIES. 


The  electro-magnetic  balancing  mechanism  consists  of  a 
weight  holder  and  an  electro- magnet,  together  with  the  contact 
point  on  the  scale  beam,  mercury  cup,  wiring,  batteries  and  the 
necessary  fittings. 

The  weight  holder  is  a coiled  brass  tube  that  holds  about  one 
hundred  and  twenty-five  weights.  At  the  lower  end  of  this 
brass  coil  is  a lever  that  can  turn  back  and  forth  on  pivot. 
One  end  of  this  lever  is  connected  by  a link  to  the  armature  of 
the  magnet,  and  the  other  end,  which  is  held  in  place  by  a 
spring,  when  the  circuit  is  open,  has  a weight  pocket  that  takes 
one  weight  from  the  weight  tube  each  time  the  circuit  is  closed 
and  carries  it  laterally  about  five-sixteenths  of  an  inch  and  lets 
it  drop,  through  a hole  in  the  brass  plate,,  on  to  the  scale  pan. 
As  soon  as  the  circuit  is  opened  again  by  the  readjustment  of 
the  scale  beam  the  lever  returns  to  its  position  and  receives 
another  weight  from  the  tube,  and  is  again  ready  to  drop  it 
into  the  scale  pan  as  soon  as  the  necessary  increase  in  weight 
to  close  the  circuit  at  the  other  end  of  the  beam  has  taken 
place. 

The  weight  holder  has  a calibre  one-sixteenth  of  an  inch 
larger  than  the  diameter  of  the  weights  used.  It  is  screwed  to 
the  frame  of  the  electro-magnet  and  extends  upward  and  to 
the  outside  of  the  case  for  the  reception  of  the  new  weights  at 
its  exterior  end.  It  is  made  air  and  water  tight  from  the  ex- 
terior by  means  of  a rubber  stopper  that  fits  into  the  case. 
The  weight  holder  can  therefore  be  taken  out  and  replaced  by 
one  of  greater  or  less  calibre,  depending  upon  the  size  of  the 
weights  used,  thus  if  two  tubes,  five-sixteenths  and  one-fourth 
inch  respectively,  are  used,  two  sets  of  weights  can  be  put  in, 
viz,:  one-fourth  inch  weighing  about  one  gram,  and  three-six- 
teenth inch  weighing  about  one  half  a gram.  Larger  or 
smaller  sizes  could  be  used,  but  for  growth  or  transpiration  the 
above  sizes  are  sufficiently  delicate  to  give  a good  curve. 

The  weights  used  are  steel  balls,  the  same  make  and  size  as 
are  used  in  bicycle  bearings.  These  are  perfectly  accurate, 
not  varying  in  diameter  more  than  one  two  thousandths  of  an 
inch,  and  in  weight  on  an  average  not  more  than  one  thous- 
andth of  a gram.  Sets  of  these  balls  can  of  course  be  weighed 
and  verified  by  the  experimenter  himself. 

The  electro-magnet  has  a single  coil,  and  one  end  of  the  core 
is  joined  with  the  frame  of  the  magnet  which  forms  the  return 
magnetic  circuit.  The  other  end  of  the  core  is  contracted  in  the 
form  of  a paraboloid. 


Anderson:  registering  balance.  179 

The  armature  having  a recess  to  correspond  with  this  para- 
boloid, is  placed  between  the  two  sides  of  the  frame,  being 
pivoted  at  one  end;  the  other  end  has  a lever  communicating 
with  the  weight  dropping  mechanism  by  a connecting  link. 
This  construction  of  the  magnet  gives  a double  magnetic  cir- 
cuit of  low  resistance,  and  also  a maximum  pull  and  greater 
range  of  movement  of  the  armature.  The  current  from  a sin- 
gle good  carbon-zinc  cell  is  sufficient  to  operate  the  weight 
dropping  mechanism.  The  current  from  the  battery  passes 
through  the  magnet  to  a mercury  cup,  thence  through  a pla- 
tinum contact  point  on  the  scale  beam  to  the  binding  post  on 
the  case  and  back  to  the  battery. 

The  case  is  twelve  by  eighteen  inches  and  is  made  of  ena- 
melled sheet  iron  riveted  to  a frame  work  of  wrought  iron.  The 
edges  of  the  sheet  iron  are  turned  in  so  as  to  make  with  the 
frame  work  a groove  on  each  side  for  two  sliding  glass  doors. 
Thus  the  whole  inside  of  the  registering  balance  can  be  seen 
and  watched  from  without,  and  either  side  of  the  case  opened 
as  desired.  The  case  is  leveled  by  means  of  four  milled  headed 
brass  screws.  A circular  spirit  level  is  placed  on  the  iron 
plate  immediately  in  front  of  the  scale  beam  supports  and  thus 
the  entire  apparatus  can  be  leveled  in  a few  moments.  The 
whole  case  is  made  so  that  it  can  be  used  in  a green-house  or 
in  the  open  air  without  interference  from  moisture  or  rain. 

The  registering  balance  can  be  used  for  registering  any  con- 
tinuous increase  in  weight.  For  transpiration  a combined 
calcium  chloride  and  sulphuric  acid  absorber  is  placed  on  one 
scale  pan,  and  the  previously  dried  air  that  takes  up  the  trans- 
pired moisture  from  the  plant  chamber  (bell  glass)  is  forced 
through  the  absorber  by  means  of  an  aspirator.  Two  light 
pieces  of  rubber  tubing  connect  the  absorber  with  the  plant 
chamber  and  aspirator,  by  means  of  pieces  of  glass  tubing  in 
rubber  stoppers  fitted  into  the  case.  The  rubber  tubes  are 
thus  inside  of  the  case  and  can  not  be  disturbed  by  any  outward 
influence.  They  buoy  up  and  down  with  the  scale  pan  and 
absorber.  In  balancing  the  scale  for  the  beginning  of  an  ex- 
periment these  pieces  of  rubber  tubing  are  partly  weighed  and 
continue  to  be  a part  of  the  weight  on  the  absorber  pan,  but  as 
their  weight  is  approximately  constant  no  error  results. 

An  attachment  is  made  to  the  balance  when  used  for  weigh- 
ing large  fruits,  which  necessarily  must  be  grown  outside  of 
the  case.  This  is  made  by  elongating  the  scale  pan  support  to 


180 


MINNESOTA  BOTANICAL  STUDIES. 


the  exterior  by  means  of  a light  brass  tube.  One  scale  pan 
will  then  be  on  the  outside  of  the  case  and  can  be  used  for  the 
growing  fruit. 

In  the  preliminary  experiments  on  transpiration  this  appa- 
ratus has  been  found  to  eliminate  a large  proportion  of  the 
errors  usually  attending  this  work,  while  it  is  of  equal  value  in 
work  on  growth  increase  of  weight. 

See  Plate  VII. 


XVII.  ON  A NEW  ELECTRIC  AUXANOMETER 
AND  CONTINUOUS  RECORDER. 

W.  D.  Frost. 


THE  ELECTRIC  AUXANOMETER. 

In  undertaking  recently  some  work  on  growth  in  thickness 
it  was  found  that  there  was  no  available  auxanometer  suitable 
for  the  exact  needs  of  the  line  of  experiments  designed. 
Pfeffer’s  auxanometer  was  the  best  instrument  within  reach  of 
the  writer,  and  while  this  is  adapted  for  work  with  moderately 
large  plants  it  is  too  cumbersome  for  delicate  ones,  as  the 
counter-weight  required  to  overcome  the  friction  of  the  pulleys 
is  sufficient  to  produce  abnormal  conditions.  In  the  measure- 
ment of  growth  in  thickness  of  stems,  fruits,  etc. , it  seemed 
absolutely  necessary  that  the  whole  instrument  used  should  be 
attached  to,  and  suspended  from  the  plant,  to  avoid  any  error 
caused  by  movements,  such  as  twisting  or  bending,  due  to  hel- 
iotropism  or  geotropism. 

To  meet  these  conditions  the  only  contrivance  which  seemed 
possible  was  one  in  which  a very  small  increment  of  growth 
should  momentarily  close  an  electric  circuit  by  means  of 
some  easily  adjustable  mechanism.  The  increment  of  growth 
necessary  to  close  the  circuit  being  constant,  successive 
closures  of  the  circuit  could,  of  course,  easily  be  registered. 

A working  model  was  constructed  upon  this  principle,  and  it 
proved  so  successful  that  it  has  been  put  in  permanent  shape 
by  the  instrument  maker  of  the  laboratory.  It  has  further- 
more seemed  advisable  to  print  here  a description  of  it  in  ad- 
vance of  the  results  from  its  use  in  investigations  now  in  pro- 
gress in  the  laboratories  for  plant  physiology  of  the  University 
of  Minnesota. 

While  it  was  originally  intended  for  measuring  growth  in 
thickness,  yet  it  is  equally  efficient  in  measuring  growth  in 
length.  Its  extreme  lightness  and  delicacy  make  it  especially 
useful  in  measuring  *the  growth  of  small  plants,  and  since  it  is 


182 


MINNESOTA  BOTANICAL  STUDIES. 


constructed  of  aluminum,  it  can  be  used  on  plants  while  they 
are  under  normal  conditions  of  moisture,  without  injury  to  the 
instrument.  The  auxanometer  proper  can  be  separated  an  in- 
definite distance  from  the  registering  apparatus.  Registrations 
have  already  been  made  in  the  laboratory  of  the  growth  of 
plants  under  natural  conditions,  400  yards  distant  and  in 
another  building. 

The  auxanometer  consists  of  a ratchet-wheel  on  a steel 
axis  which  also  bears  a series  of  small  grooved  wheels  1, 
3-J  and  6 mm.  in  diameter,  and  a somewhat  larger  wheel 
upon  which  is  wound  a thread  bearing  a counter-weight.  The 
diameter  of  the  larger  wheel,  is  about  5 cm.  and  the  circum- 
ference contains  144  notches.  A ratchet  which  fits  in  the 
notches  of  this  wheel,  is  mounted  on  an  axis  similar  to  that  of 
the  others,  and  has  a long  horizontal  arm.  This  arm  has  a 
platinum  tip.  As  the  large  wheel  turns,  the  ratchet  drops 
into  the  notches  in  its  circumference  and  the  platinum  tip  is 
lowered  so  that  it  touches  a drop  of  mercury  which  is  held  in 
a small  cup  on  the  arm  of  the  frame.  This  arm  is  insulated 
from  the  rest  of  the  instrument  and  is  connected  by  means  of  a 
small  wire,  to  one  pole  of  an  electric  battery.  The  other  part 
of  the  instrument  is  connected  with  the  other  pole  of  the 
battery.  The  screw  underneath  enables  the  height  of  the 
mercury  to  be  regulated,  and  consequently  the  length  of  time 
which  the  current  remains  closed  or  open. 

The  frame  work  of  the  instrument  is  made  of  aluminum, 
and  entire  weighs  15  gms.  It  may  be  attached  to  the  arm  of  a 
tripod  support,  and  in  this  position  can  be  used  for  measuring 
growth  in  length,  (as  shown  in  Plate  x).  For  measuring  growth 
in  thickness  the  instrument  can  be  fastened  to  the  support  and 
held  against  the  stem,  or  fruit,  which  is  to  be  measured,  or  it 
can  be  removed  from  the  support  and  attached  to  the  plant. 
When  attached  directly  it  is  held  in  place  by  a clamp.  This 
can  be  entirely  removed  and  placed  around  the  plant.  It  is 
roughly  adjusted  in  place  by  means  of  a catch,  which  fits  into 
the  notches  on  the  clamp.  The  fine  adjustment  is  ac- 
complished by  a screw.  When  the  apparatus  is  in  place  a silk 
thread  is  fastened  to  the  hook  on  the  frame,  passed  around 
the  plant  in  the  direction  opposite  the  hands  of  a clock,  so 
that  the  thread  may  be  in  contact  with  the  entire  circumference 
of  the  plant.  The  thread  is  then  passed  through  a hole  in  the 
axis  of  the  auxanometer  where  it  is  securely  fastened  and  the 


Frost:  auxanometer  and  continuous  recorder.  183 


counter-weight  on  the  wheel  is  made  sufficient  to  keep  taut 
the  thread  which  passes  around  the  plant. 

As  the  plant  increases  in  thickness  the  thread  is  unwound 
from  the  pulley  upon  which  it  was  previously  wound;  and  as 
this  turns,  and  the  teeth  of  the  large  wheel  pass  the  ratchet, 
the  electric  current  is  alternately  opened  and  closed. 

In  measuring  growth  in  length  the  instrument  is  supported 
above  the  plant  and  the  thread  passed  from  the  growing  part 
to  the  small  wheels.  If  the  smallest  wheel  is  used,  during  the 
growth  of  a millimeter,  46  registrations  are  made,  that  is  to 
say  one- forty- sixth  of  a mm.  in  length  causes  the  circuit  to  be 
closed,  while  the  largest  wheel  registers  a growth  of  one- 
seventh  of  a millimeter. 

See  Plate  VIII. 

THE  CONTINUOUS  RECORDER. 

This  part  of  the  apparatus  consists  essentially  of  two  rollers, 
one  of  which  is  attached  to  a clock  train,  and  as  it  revolves 
winds  upon  itself  a ribbon  of  paper  on  the  other  roller, 
and  an  electro-magnet,  to  the  armature  of  which  is  at- 
tached a pen  that  presses  against  the  paper  on  the  second 
roller.  While  the  circuit  remains  open  a continuous  line  is 
traced  near  one  edge  of  the  paper  ribbon.  When  the  circuit  is 
closed  the  pen  is  drawn  to  the  other  side  of  the  paper  and  the 
length  of  the  line  traced  there  denotes  directly  the  length  of 
time  that  the  circuit  is  closed. 

The  clock  train  is  an  eight  day  lever  movement  with  strong 
double  springs.  The  case  which  is  seven  inches  in  diameter 
is  finished  in  brass,  and  is  so  attached  to  the  base  that  it  can  be 
easily  removed.  Projecting  through  the  front  of  the  case  is 
the  pinion  by  which  the  rollers  are  turned.  This  pinion  re- 
volves once  in  twelve  hours,  carrying  with  it  the  roller 
made  of  brass  carefully  turned  and  balanced.  It  is 
slightly  less  than  four  inches  in  diameter;  thus  the  paper 
moves  at  a rate  of  one  inch  per  hour.  It  has  quarter  inch 
flanges,  and  an  arrangement  by  which  the  end  of  the  paper  is 
held  in  place.  On  the  outer  surface  of  this  roller  is  a dial 
plate  with  the  lettering  opposite  to  that  on  an  ordinary  clock. 
Upon  the  support  is  a pointer.  By  means  of  this  arrangement 
the  time  indicated  by  the  clock  can  be  read  within  a few  min- 
utes. 

The  second  roller,  with  the  exception  of  the  dial,  is  exactly 
similar  to  the  first.  Both  are  mounted  on  steel  shafts,  turned 


184 


MINNESOTA  BOTANICAL  STUDIES. 


to  fit  the  bearings.  The  supports  are  made  of  brass  and  screwed 
to  a black  walnut  base,  which  is  built  of  narrow  strips  to 
prevent  warping. 

The  paper  ribbon  on  which  the  record  is  obtained  is  two- 
thirds  of  an  inch  in  width  and  made  in  two  lengths,  one  suffi- 
ciently long  to  run  four  and  the  other  eight  days.  Across  the 
upper  surface  of  the  paper  ribbon  is  printed  a series  of  lines 
that  divide  the  ribbon  into  hour  spaces,  which  are  numbered 
consecutively.  These  hour  spaces  are  so  ruled  that  the  time 
of  registration  can  be  read  to  one  minute  directly  from  the 
ribbon. 

A source  of  error  arising  from  the  fact  that  the  paper  as 
it  is  wound  on  the  first  roller  increases  the  circumference  of 
the  roller,  and  causes  the  paper  to  move  at  an  increased  rate 
as  the  paper  continues  to  be  wound  up,  is  avoided  by  having 
each  successive  hour-space  longer  than  the  preceding  one.  The 
correction,  however,  is  very  slight  on  account  of  the  thinness 
of  the  paper  used,  and  would  amount  to  only  six  minutes  at  the 
end  of  the  eighth  day. 

The  time  marker  consists  of  a pen  made  of  brass,  and  large 
enough  to  hold  an  amount  of  aniline  ink  sufficient  for  two 
weeks  registration.  This  pen  is  attached  by  means  of  a rolled 
brass  strip  to  the  armature  of  an  electro-magnet,  which  is 
hung  on  a hinge  close  to  the  base.  Thus,  as  the  armature 
moves  in  response  to  the  attraction  of  the  magnet,  or  the  pull 
of  a tension  spring,  the  pen  is  drawn  through  a short  hori- 
zontal distance.  The  rod  simply  serves  as  a support  to  the 
pen.  The  pen  presses  against  the  paper  on  the  roller,  and  by 
means  of  the  milled  nut  it  can  be  kept  at  any  required  pressure, 
or  can  be  withdrawn  from  the  paper  entirely  when  the  latter 
is  to  be  removed  or  replaced. 

When  the  circuit  is  open  the  armature  is  held  back  by  the 
tension  spring,  and  the  length  of  the  brass  strip  is  so  arranged 
that  the  pen  then  traces  a line  near  the  right  hand  side  of  the 
ribbon,  as  it  is  shown  in  the  plate.  When  the  circuit  is  closed 
the  armature  is  attracted  and  the  pen  is  pushed  to  the  other 
side  of  the  paper  ribbon,  thus  making  a short  line  at  right 
angles  to  the  length  of  the  paper.  If  the  circuit  is  immediately 
opened  the  time  of  registration  is  marked  simply  by  a single 
cross  mark.  If,  however,  the  circuit  remains  closed  for  some 
time  a line  is  traced  on  the  left  side  of  the  paper. 

In  reading  the  record  in  this  case  the  length  of  time  elaps- 
ing between  two  successive  closures  of  the  circuit,  is  indicated 


Frost:  AUXANOMETER  AND  CONTINUOUS  RECORDER.  185 


by  the  distance  between  the  two  successive  forward  movements 
of  the  pen,  or,  what  is  the  same  thing,  the  length  of  the  line 
traced  while  the  circuit  is  closed,  plus  the  length  of  the  line 
made  while  the  circuit  is  open,  as  any  one  notch  passes  the 
ratchet. 

The  auxanometer  is  connected  with  the  registering  appa- 
ratus and  an  electric  battery.  The  battery  is  of  a type  suited 
for  a closed  circuit.  The  two  instruments  may  be  placed  upon 
the  same  table,  or  they  may  be  separated  any  distance,  as 
is  most  convenient  for  the  operator. 

This  recorder  may  also  be  used  with  many  other  kinds  of 
apparatus  wherever  a continuous  record  is  desired. 

See  Plate  IX. 


XVIII.  TITLES  OF  LITERATURE  CONCERNING 
THE  FIXATION  OF  FREE  NITROGEN  BY 
PLANTS. 

D.  T.  Mac  Dougal. 


The  relations  sustained  by  plants  to  the  nitrogen  compounds 
of  the  soil  and  water,  and  to  the  free  nitrogen  of  the  air  form  a 
subject  of  great  biological  import,  and  since  aside  from  its 
purely  scientific  aspect  certain  phases  of  the  main  question 
are  of  vast  practical  interest  they  have  attracted  the  attention 
of  the  agriculturist  and  chemist  as  well  as  of  the  botanist. 

The  results  of  the  investigations,  from  these  various  points 
of  view,  which  have  been  in  progress  for  a century,  form  a mass 
of  literature  which  is  scattered  through  the  journals  and  pro- 
ceedings of  the  various  branches  of  natural  science  in  such 
manner  as  to  be  very  difficult  of  access  to  the  student  with 
ordinary  facilities. 

Among  this  rich  and  withal  unwieldy  mass  of  literature  the 
part  of  especial  interest  to  the  botanist  is  that  which  concerns 
the  fixation  of  free  nitrogen  by  the  leguminous  plants  and  the 
organism  found  in  the  tubercles  which  characterize  this  group, 
and  the  fixation  of  free  nitrogen  by  green  plants  which  do  not 
sustain  mutualistic  relations  to  the  lower  organisms. 

The  large  number  of  controversies  resulting  from  the  attain- 
ment of  radically  different  conclusions  from  similar  experiments 
along  certain  lines  of  the  work,  in  the  hands  of  various  investi- 
gators, leads  to  the  belief  that  safe  generalizations  can  be  made 
from  the  restricted  groups  of  facts  thus  obtained  only  when 
confirmed  by  extended  and  parallel  researches.  To  meet  this 
idea  the  references  given  below  concern  the  points  of  central 
interest  to  the  botanist,  beside  a number  of  titles  to  ‘ ‘ nitrifica- 
tion,” and  to  cases  of  mutualism  and  symbiosis  which  may 
* offer  a comparison  however  distant  with  the  relations  existing 
between  the  leguminous  plant  and  the  tubercle  organism. 


Mac  Dougal:  fixation  of  free  nitrogen. 


187 


The  list  is  composed  of  titles  which  have  been  incidentally 
collected  by  Professor  MacMillan  and  the  writer,  and  are  com- 
prised in  the  card  catalogue  of  the  botanical  department  of  the 
University  of  Minnesota.  Their  presentation  in  this  form  is 
for  the  purpose  of  making  them  still  more  readily  available  to 
students  and  investigators  in  connection  with  this  department, 
and  wherever  this  line  of  work  is  carried  forward.  It  is  pur- 
posed to  bring  out  a second  installment  of  titles  which  the 
writer  in  the  limited  time  at  his  disposal  was  not  able  to  prepare 
for  this  number. 

Allen  E.  W.  Leguminous  plants  for  green  manuring  and  for 
feeding.  U.  S.  Dept.  Ag.  Farm.  Bull.  No.  16.  1894. 

Lllpe  and  Menozzi.  Bull.  d.  notize  agrarie  d.  Ministere  d’ 
Agric.  No.  14.  1892. 

Andre.  See  Berthelot. 

-Arcangeli.  Sopra  i tubercoli  radicali  delle  Leguminose.  Atti 
del.  real.  Accad.  d.  Lincei,  7 : Fasc.  6,  223.  1891. 

■ Atkinson  G.  F.  Science  Coni  Ala.  Ex.  Sta.  1 : 1.  1889. 

t Atkinson  G.  F.  The  genus  Frankia  in  the  United  States.  Bull. 
Torr.  Bot.  Club  19: 171  1892. 

Atkinson  G.  F.  Tubercles  of  Ceanothus.  Bot.  Gazette 
16:262.  1891. 

‘'Atkinson  G.  F.  Contributions  to  the  biology  of  the  organism 
causing  leguminous  tubercles.  Bot.  Gazette  18:157, 
226,257.  1893. 

Atkinson  G.  F.  Symbiosis  in  the  roots  of  the  Ophioglossaceae. 

Bull.  Torr.  Bot.  Club  20 : 356.  1893. 

Atwater  and  Rockwood.  On  the  loss  of  nitrogen  during  germ- 
ination and  growth.  Am.  Chem.  Jour.  8 : 327.  1868. 

Atwater  W.  0.  On  the  assimilation  of  atmospheric  nitrogen 
by  plants.  Rep.  Brit.  A.  A.  S.  685.  1884. 

^Atwater  W.  0.  Absorption  of  atmospheric  nitrogen  by  plants. 

Am.  Chem.  Jour.  6:365.  1885;  also,  12:526.  1891^; 

also,  13:42.  1891. 

i-Atwater  and  Woods.  Atmospheric  nitrogen  as  plant  food. 

Conn.  Storrs  Ag.  Ex.  Sta.  Rep.  2:11.  1889;  also, 

3:12.  1890. 

Atwater  and  Woods.  The  fixation  of  free  nitrogen  by  plants. 

Conn.  Storrs  Ag.  Ex.  Sta.  Rep.  5:17.  1892. 

Atwater  W.  0.  On  the  liberation  of  nitrogen  from  its  com- 
pounds, and  the  acquisition  of  atmospheric  nitrogen 
by  plants.  Am.  Chem.  Jour.  8:  398.  1868. 


188 


MINNESOTA  BOTANICAL  STUDJES. 


Atwater  and  Woods.  Absorption  of  atmospheric  nitrogen  by" 
plants.  Am.  Chem.  Jour.  13:42.  1891. 

Babes*  Cornil  et.  Bacteries  du  sol.  Les  Bacteries,  1:213. 
1890. 

Bary  A.  de  Morphologie  und  Physiologie  der  Pilze,  Flechten 
und  Myxomyceten.  1866. 

Bary  A.  de  Die  Erscheinung  der  Symbiose.  1879. 

Benecke  F.  Ueber  die  Mykorhiza.  Biol.  Centralb.  4:753,  781. 
1888. 

Benecke  F.  Ueber  die  Knollchen  an  den  Leguminosen-Wurz- 
eln.  Bot.  Centralb.  29*:  53.  1887. 

' Berg  F.  Das  nitrificierende  Ferment  des  Bodens.  Sitzungsb. 
Naturf.  Ges.  Dorpat.  10:  No.  1.  1892. 

Berggren  S.  Om  rotbildningen  hos  australa  Coniferer.  Bot. 
Notiser.  144.  1887. 

Berthelot.  Sur  l’absorption  de  l’azote  libre  par  les  principes 
immediats  des  vegetaux  sous  l’inlluence  de  l’electricite. 
Jour.  f.  Pharm.  24:433.  1876. 

Berthelot.  Sur  l’absorption  de  Tazote  libre  par  les  principes 
immediats  des  vegetaux  sous  l’influence  de  l’electricite 
atmospherique.  Compt.  rend.  83:677.  1876. 

Berthelot.  Sur  l’absorption  de  l’azote  libre  par  les  principes 
immediats  des  vegetaux  sous  l’inlluence  de  l’electricite. 
Ann.  d.  Chim.  et  Phys.  10:  55.  1877. 

Berthelot  and  Andre.  “Nitrates  in  plants.”  Jour.  f.  Pharm. 
_ et  Chim.  1884. 

Berthelot.  Fixation  directe  de  l’azote  atmospherique  libre  par 
certaines  terrains  argileux.  Compt.  rend.  101:  1885. 

Berthelot  and  Andre.  Sur  les  principles  azotees  de  la  terre 
vegetaie.  Compt.  rend.  103:1101.  1886. 

Berthelot.  Sur  la  fixation  directe  de  l’azote  gazeux  de  l’atmos- 
phere  par  les  terres  vegetales.  Compt.  rend.  104:205. 

1887. 

Berthelot.  Sur  la  fixation  de  1’azote  gazeux  de  1' atmosphere 
par  les  terres  vegetales,  avec  le  concours  de  la  vege- 
tation. Compt.  rend.  104:625.  1887. 

Berthelot.  Experiences  nouvelles  sur  la  fixation  de  l’azote  et 
par  certaines  terres  v6g6 tales  et  par  certaines  plantes. 
Compt.  rend.  106:372.  1888. 

Berthelot.  Sur  quelques  conditions  generates  de  la  fixation 
de  l’azote  par  la  terre  vegetaie.  Compt.  rend.  106:  569. 

1888. 


Mac  Dougal:  fixation  of  free  nitrogen. 


189 


Berthelot.  Sur  la  transformation  dans  le  sol  des  azotates  en 
composes  organiques  azotes.  Compt.  rend.  106:638. 
1888. 

Berthelot.  Observations  snr  la  fixation  de  l’azote  par  certaines 
sols  et  terres  vege  tales.  Compt.  rend.  106: 1049.  1888. 

Berthelot.  Sur  la  fixation  de  l’azote  par  la  terre  vegetale. 
Compt.  rend.  106:1214.  1888. 

Berthelot.  Experiences  nouvelles  sur  la  fixation  de  l’azote  par  . 
certaines  terres  v^getales  et  par  certaines  plantes. 
Ann.  d.  Chim.  et  Phys.  16.  1889. 

Berthelot  and  Andre.  Faits  pour  servir  a l’histoire  des  prin- 
cipes  azotes  renfermes  dans  la  terre  vegetale.  Ann.  d. 
Chim.  et  Phys.  6 ser.  2 5 : 314.  1892. 

Berthelot.  Sur  la  fixation  de  l’azote  dans  les  oxydation  len- 
tes.  Compt.  rend.  108:543.  1889. 

Berthelot.  Fixation  de  1’ azote  par  la  terre  vegetale  nue  ou 
avec  le  concours  des  Legumineuses.  Compt.  rend. 
108:700.  1889. 

^Berthelot.  Recherches  nouvelles  sur  la  fixation  de  l’azote  par 
la  terre  vegetale.  Influence  del  electricite.  Compt. 
rend.  109:281.  1889. 

^Berthelot.  Sur  les  relations  de  l’azote  atmospherique  avec  la 
terre  vegetale.  Compt.  rend.  109: 345.  1889. 

v Berthelot.  Sur  la  fixation  de  l’azote  atmospherique.  Compt. 
rend.  109:417.  1889. 

^Berthelot.  Observations  sur  la  formation  de  l’ammoniaque  et 
de  composes  azotes  volatils  aux  depens  de  la  terre 
vegetale  et  des  plantes.  Compt.  rend.  109:419.  1889. 

1 Berthelot.  Remarques  sur  la  formation  des  azotates  dans  les 
vegetaux.  Compt.  rend.  110: 109.  1890. 

-Berthelot.  Observations  sur  la  note  precedente  de  Schloesing 
fils  et  Em.  Laurent.  Compt.  rend.  Ill : 753.  1890. 

Berthelot.  Observations  sur  les  reactions  entre  la  terre  vege- 
tale et  l’ammoniaque  atmospherique.  Compt.  rend. 
111:558.  1890. 

Berthelot  and  Andre.  Faits  pour  servir  a l’histoire  des  prin- 
cipes  azotes  renfermes  dans  la  terre  v6g6tale.  Compt. 
rend.  112:189.  1891. 

Berthelot.  Nouvelles  recherches  sur  la  fixation  de  l’azote  par 
les  microbes.  Compt.  rend.  115:  569.  1892. 

^Berthelot.  Recherches  nouvelles  sur  les  micro- organismes 
fixateurs  de  l’azote.  Compt.  rend,  116:842.  1893, 


190 


MINNESOTA  BOTANICAL  STUDIES. 


Berthelot.  Observations  relativus  a une  note  de  Winograd- 
sky Snr  l’assimilation  de  l’azote  gazeux  de  l’atmosphere 
par  les  microbes.  Comp t.  rend.  116:1388.  1893. 

Berthelot.  Nouvelles  recherches  snr  les  micro- organismes 
fixateurs  de  l’azote.  Ann.  d.  Cfrmi,  et  Phys,  30:419. 
1893. 

Berthelot.  Nouvelles  recherches  sur  la  fixation  de  l’azote 
atmospherique  par  les  micro- organismes.  Ann.  d. 
Chim.  et  Phys.  30:411.  1893. 

Berthelot.  Sur  une  methode  destinee  a etudier  les  echanges 
gazeux  entre  les  etres  vivants  et  l’atmosphere  que  les 
entoure.  Compt.  rend.  118 : 112.  1894. 

Berthelot.  Nouvelles  observations  sur  les  composes  azotes 
volatils  emis  par  la  terre  vegetale.  Compt.  rend. 
118:195.  1894. 

Beyerinck  M.  W.  Die  Bacterien  der  Papilionaceen-knOllchen. 
Bot.  Ztg.  46:725,  741,  757,  780,  797.  1888. 

Beyerinck  M.  W.  Wurzelknospen.  Verh.  d.  koninkl.  Akad  v. 

Wetensch.  te  Amsterdam.  25: — . 1887.  See  also  1890. 

Beyerinck  M.  W.  Kunstliche  Infektion  von  Vicia  faba  mit 
Bacillus  radicicola:  Ernahrungsbedingungen  dieser 

Bacterie.  Bot.  Ztg.  48:838.  1890. 

Beyerinck  M.  W.  Over  ophooping  van  atmospherische  Stick- 
stoff  in  culturen  van  Bacillus  radicicola.  Vers,  en 
Meded.  der  koninkl.  Akad.  van  Wetensch.  te  Amster- 
dam. Afd.  Natuurkunde,  Hft.  3:460.  1891. 

Bohme  K.  Stickstoff-ernahrung  der  Leguminosen.  Separat 
1892.  Dresden. 

Bolley  H.  B.  Notes  on  root  tubercles  of  indigenous  and  exotic 
Legumes  in  virgin  soil  of  Northwest.  Ag.  Science 
7 : 58.  1893. 

Bonnier  G.  La  Constitution  des  Lichens.  Jour.  d.  Bot.  1: 1. 
1887. 

Bonnier  G.  Germination  des  spores  de  Lichens  sur  les  proto- 
nemas  des  Mousses.  Rev.  Gen.  d.  Bot.  1 : 165.  1889. 

Bonnier  G.  Recherches  sur  la  synthese  des  Lichens.  Ann.  d. 
Sc.  Nat  7ser.  9 :1.  1889. 

Bonorden  H.  F.  Handbuch  der  Allgemeinen  Mykologie.  1851. 

Bordier  M.  H.  “Nitrification.”  Mem.  Sc.  Phys.  et  Nat.  Bor- 
deaux 5:185.  1890. 

Borgreve.  Zusatz  zu:  Braun  zur  Mycorhiza  Frage.  Forstl. 
Bl.  13:205.  1889. 


Mac  Dougal:  fixation  of  fjree  nitrogen.  191 

t Bouche.  Zur  Unterscheidung  des  Phaseolus  vulgaris  und  Ph. 
multiflorus  Lam.  Bot.  Ztg.  10:735.  1852. 

'Boudier.  Du  parasitisme  probable  de  quelques  especes  du 
genre  Elaphomyces  et  de  la  recherche  de  ces  Tuber- 
aces.  Bull.  d.  Soc.  Bot.  d.  France,  23: — . 1876. 

Bouquet.  Eine  neue  Hypotheses  des  Absorptions  der  Stick- 
stoff  durch  Pflanzen.  Jour.  l’Ag.  Practique.  1888. 

Boussingault  J.  B.  Recherches  chimiques  sur  la  vegetation 
enteprises  dans  le  but  d’examiner  si  les  plantes  pren- 
nent  de  l’azote  de  l’atmosphere.  Ann.  Sc.  Nat.  10:257. 
1837. 

Boussingault  J.  B.  Recherches  chimiques  sur  la  vegetation 
enterprises  dans  le  but  d’examiner  si  les  plantes  pren- 
nent  de  l’azote  de  l’atmosphere,  Compt.  rend.  6 : 102. 
1838  and  7 : 138.  1838. 

Boussingault  J.  B.  Recherches  chimiques  sur  la  vegetation 
enteprises  dans  le  but  d’examiner  si  les  plantes  pren- 
nent  de  l’azote  de  l’atmosphere,  Ann.  d.  Chim.  et  Phys. 
67:35.  1838  and  69:353.  1838. 

Boussingault  J.  B.  Recherches  chimiques  sur  la  vegetation 
enteprises  dans  le  but  d’examiner  si  les  plantes  pren- 
nent  de  l’azote  de  l’atmosphere,  Jour.  f.  Prakt.  Chem. 
14:193.  1838,  and  16:385.  1839. 

'^Boussingault  J.  B.  Recherches  sur  la  vegetation,  etc.  Ann. 
d.  Chim.  41:5.  1854,  and  43: 149.  1855. 

^ Boussingault  J.  B.  Recherches  sur  la,  vegetation,  etc.  Ann. 
Sc.  Nat.  1:241.  1854. 

Boussingault  J.  B.  Recherches  sur  la  vegetation,  etc.  Jour, 
d.  Pharm.  26:127.  1854. 

'Boussingault  J.  B.  Recherches  sur  la  vegetation.  Compt. 
rend.  38:  580,  607.  1854,  and  39:  601.  1854. 

Boussingault  J.  B.  Recherches  sur  la  vegetation.  Ann.  d. 
Chim.  46:5.  1856. 

Boussingault  J.  B.  Recherches  sur  la  vegetation.  Ann.  Sc. 
Nat.  2:357.  1854. 

wBoussingault  J.  B.  Recherches  sur  la  vegetation.  Jour  f. 
Prakt.  Chem.  62:108,  181.  1854,  and  63:418.  1854. 

Boussingault  J.  B.  Recherches  sur  l’influence  que  l’azote 
assimilable  des  engrais  exerce  sur  la  production  de  la 
matiere  vegetale.  Compt.  rend.  44:940.  1857,  and 

45:833.  1857. 


192 


MINNESOTA  BOTANICAL  STUDIES. 


Boussingault  J.  B.  Recherches  sur  l’influence  que  l’azote 
assimilable  des  engrais  exerce  sur  la  production  de  la 
matiere  vegetale.  Ann.  Sc.  Nat.  7 : 5.  1857. 

Boussingault  J.  B.  Agronomie,  Chemie,  Agricole  et  Phy- 
siologie  1 : 198.  1860,  and  2 : 340.  1861. 

Boussingault  J.  B.  Sur  la  nitrification  de  la  terre  Vegetale. 
Compt.  rend.  76:22.  1873. 

Boussingault  J.  B.  Sur  la  nitrification  de  la  terre  vegetale. 
Ann.  d.  Chim.  et  Phys.  29:186.  1873. 

Boussingault  J,  B.  Sur  l’influence  que  la  terre  vegetale  exerce 
sur  la  nitrification  des  substances  azotes  d’origine  or- 
ganique  employees  comme  engrais.  Compt.  rend. 
82:477.  1876.  Also,  Ann.  d.  Chim.  8:5.  1876. 

Boutin.  Note  sur  l’origine  des  nitrates  dans  l’Amarantus  bli- 
tum.  Compt.  rend.  82:  No.  25.  1876. 

Boutroux  L.  Sur  la  fermentation  panaire.  Compt.  rend. 

112: 203.  1891.  See  also  Ann.  d.  Chim.  et  Phys.  1892. 

'Boutroux  L.  Reveux  des  travaux  sur  les  bacteries  et  les  fer- 
mentations. Rev.  Gen.  d.  Bot.  1 6 : 30.  1894. 

Bowman  J.  E.  On  the  parasitical  connection  of  Lathraea 
squamaria  and  the  peculiar  structure  of  the  subter- 
ranean leaves.  Trans.  Linn.  Soc.  16:399.  1833. 

Braun.  Zur  Mycorhiza  Frage.  Forstl.  Bl.  13: 204.  1889. 

^Breal  E.  Ann.  Agron.  1888. 

^Breal  E.  Observations  sur  la  fixation  de  l’azote  atmos- 
pherique  par  les  Legumineuses  dont  les  racines  portent 
des  nodosites.  Compt.  rend.  107:372.  1888. 

^Breal  E.  Fixation  de  l’azote  par  les  Legumineuses.  Compt. 
rend.  109:670.  1889.  110:670.  1890. 

Breal  E.  Bindung  des  Lufts  ticks  toffs  durch  Kresse  (Tropae- 
olum).  Ann.  Agron.  18:369.  1893. 

Brefeld  0.  Bot.  Untersuchungen.  1883. 

Brefeld  0.  Untersuchungen  auz  dem  Gesammtgebiete  der 
Mykologie,  3.  1877.  And  7.  1888. 

Bruchmann  H.  Ueber  Anlage  und  Wachstum  der  Wurzeln 
von  Lycopodium  und  Isoetes.  Jen.  Zeitschr.  f.  Naturw. 
New  Ser.  1 : 522.  1874. 

Bruchmann  H.  Die  Dichotomie  der  Wurzel  von  Pinus  sylves- 
tris.  Jen.  Zeitschr.  f.  Naturw.  New  Ser.  1:572.  1874. 

Bruchmann  H.  Das  Prothallium  von  Lycopodium.  Bot.  Cen- 
tralb.  21:23,  309.  1885. 


Mac  Dougal:  fixation  of  free  nitrogen. 


193 


Brunchorst  B.  Ueber  die  Knollchen  an  der  Wurzeln  von 
Alnns  nnd  den  Eleagnaceen.  Bot.  Centra  lb.  24:  222. 
1885. 

Brunchorst  B.  Ueber  die  Knollchen  an  den  Leguminosen- 
wnrzeln.  Ber.  d.  deut.  Bot.  Ges.  3:  Hft.  7,  241.  1885. 

v Brunchorst  B.  Ueber  einige  Wurzelanschwellungen,  besond- 
ers  diejenigen  von  Alnus  and  Elaeagnaceen.  Unter- 
such.  Bot.  Inst.  z.  Tubingen,  2:151.  1886. 

Brunchorst  B.  Die  Struktur  der  Inhaltskftrper  in  den  Zellen 
einiger  Wurzelanschwellungen.  Sep.  a.  Bergens  Mus. 
Arsberetning.  235.  1887. 

» Buscalioni,  Si  contengono  bacteri  nei  tubercoli  radicati  delle 
Leguminose.  Malphigia  1 : 21,  464.  1887. 

*Cloez  S.  Recherches  experimentales  sur  la  nitrification  et  sur 
la  source  de  l’azote  dans  les  plantes.  Compt.  rend 
41:935.  1855. 

~Uloez  S.  Lettre  a M.  Chevreul  concernant  les  experiences  de 
M.  Yille  sur  la  question  de  l’assimilation  de  l’azote  de 
l’air  par  les  vegetaux.  Compt.  rend.  41:775.  1855. 

aUIocz  S.  Recherches  experimentales  sur  la  nitrification  et  sur 
la  source  de  l’azote  dans  les  plantes.  L’lnstitute  23: 
417.  1855. 

Cloez  S.  Recherches  experimentales  sur  la  nitrification  et  sur 
la  source  de  l’azote  dans  les  plantes.  Jour.  f.  Prakt. 
Chem.  68:138.  1856. 

Cloez  8.  See  Gratiolet. 

, Clos  D.  Ebauche  de  la  rhizotaxie  1848.  Paris. 

Clos  D.  Du  collet  dans  les  plantes  et  de  la  nature  de  quelque 
tubercles.  Ann.  d.  Sc.  Bot.  3:  13.  1849. 

vClos  D.  Du  collet  dans  les  plantes  et  de  la  nature  de  quelques 
tubercules.  Ann.  Sc.  Nat.  13:5.  1850.  See  also 

Soc.  Philom.  Proc.  Verb.  34.  1850. 

MDlos  D.  Revision  des  tubercles  des  plantes  et  des  tuberculoides 
des  Legumineuses,  Mem.  d.  l’Acad.  d.  Toulouse  9 ser. 
5.  1.  1893. 

^Canevari  A.  La  nutrizione  delle  piante  il  terreno  e la  conci- 
mazione,  L’ltalia  agricolia  1 9.  1887. 

^Chevreul  E.  Sur  le  role  de  l’azote  atmosph^rique  dans 
1’economie  vegetale.  Compt.  rend.  107:1460.  1888. 

v*Chuard  E.  Sur  V existence  de  phenom^nes  de  nitrification 
dans  les  mileux  riches  en  substance  organiques  et  a 
reaction  acids.  Compt.  rend.  1 14  : 181.  1892. 


194 


MINNESOTA  BOTANICAL  STUDIES. 


iCOhn  F.  Ueber  parasitic  Algen.  Beitr.  z.  Biol.  1 : Hft.  2 : 87. 

1872. 

Cohn  F.  Zur  Geschichte  der  Leguminosenknollchen.  Centralb. 

f.  Bakt.  u.  Par-Kunde.  10:  No  6,  190.  1891. 

“ Coignet  J.  De  l’absorption  de  l’azote  par  les  vegetaux.  Ann. 

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and  3 : 56.  1891  and  1892. 

vConn  H.  W.  Free  nitrogen  assimilation.  Bull.  Torr.  Bot. 
Club  20: 148.  1893. 

Corda  A.  K.  J,  leones  Fungorum  hucusque  cognitorum.  1837, 
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^Cornil  et  Babes.  Bacteries  du  sol.  Les  Bacteries  1:213. 
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Cornu.  Commission  du  Phylloxera.  1876. 

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vCrochetelle  et  Dumont.  Sur  la  nitrification  des  terre  de 
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Deherain  P.  P.  Sur  l’absorption  de  l’azote  par  les  plantes. 
Bull.  Soc.  Chim.  16:2.  1871. 

Deherain  P.  P.  Sur  l’intervention  de  1’ azote  atmospherique 
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And  76:1390.  1873. 

Deherain  P.  P.  Sur  l’intervention  de  l’azote  atmospherique 
dans  la  vegetation  Bull.  Soc.  Chim.  1 9 : 538.  1873. 

Deherain  P.  P.  Sur  Intervention  de  l’azote  atmospherique 
dans  la  vegetation.  Jour.  d.  Pharm.  18:  95.  1873. 

‘"Deherain  P.  P.  Sur  l’intervention  de  l’azote  atmospherique 
dans  la  vegetation.  Ann.  Sci.  Nat.  5 Ser.  18:147. 

1873. 

• Deherain  P.  P.  Sur  l’intervention  de  l’azote  atmospherique 
dans  la  vegetation.  Chem.  News.  29:271.  1874. 

Deherain  P.  P.  Sur  l’enrichessement  en  azote  d’un  sol  main- 
tenu  en  prairie.  Compt.  rend.  101.  1885. 

^Deherain  P.  P.  Le  travail  du  sol  et  la  nitrification.  Ann 
Agron.  19:401.  1893. 


Mac  Dougal:  fixation  of  free  nitrogen. 


195 


^Deherain  P.  P.  Le  travail  de  la  terre  et  la  nitrification. 
Compt.  rend.  116:1091.  1893. 

l/Delpino.  Osservazioni  sopra  batteriocecidii  la  sorgente  l’azote 
in  una  piante-Galega  officinalis.  Malphigia  2 : 385. 
1888. 

Saussure.  Recherches  sur  la  vegetation.  206.  1804. 

HDetmer.  Physiol.  Chem.  Unters.  uber  Keimung  68.  1875. 

>dDevaux.  Circulation  passive  de  l’azote  dans  les  vegeta  ux. 
Jour.  d.  Bot.  5:130.  1891. 

"Devaux.  Les  echanges  gazeux  d’un  tubercle,  representes 
schematiquement  par  un  appareil  physique,  Bull. 
Soc.  Bot.  d.  France.  37:257.  1891. 

Devaux.  Atmosphere  interne  des  tubercules  et  racines  tuber- 
culeuses.  Bull.  d.  Soc.  Bot.  d.  France.  37:272.  1890. 

De  Yogue.  Fixation  de  l’azote  ammoniacal  sur  la  paille. 
Compt.  rend.  1 1 5 : 25.  1892. 

/^De  Tries.  Wachstumgeschichte  des  roten  Klees.  Landw. 
Jahrb.  6:933.  1877. 

v-Douliot  et  van  Tieghem.  Recherches  comparatives  sur 
l’origine  des  membres  endogenes  dans  les  plantes  vas- 
culaires.  Ann.  d.  Sc.  Nat.  7 Ser.  8:1.  1888. 

Drouin.  See  Gautier. 

Duchartre  P.  Note  sur  l’Hypopitys  multiflora  Scop.  Ann.  d. 
Sc.  Nat.  3 Ser.  6:29.  1846. 

Duclaux.  La  distribution  de  la  matiere  organique  et  des 
microbes  dans  le  sol.  Ann.  Inst.  Past.  7 : 823.  1893. 

« Duhamel  du  Moneeau.  La  Physique  des  Arbres.  1758. 
Dumont  et  Crochetelle.  Sur  la  nitrification  des  terres  de 
prairie.  Compt.  rend.  117:670.  1893. 

Drobnig.  Beitrage  zur  Kenntniss  der  WurzelknSllen.  Inaug. 
Diss.  1892.  Rbstock. 

Drude  0.  Die  Biologie  von  Monotropa  Hypopitys  L.  und  Neot- 
tia  Nidus  avis  L.  1873.  Gottingen. 
i<Ehrenberg  A.  Weitere  Untersuchungen  tieber  die  Frage  nach 
dem  Freiwerden  von  gasformigen  Stickstoff  bei  Faul- 
niss-processen.  Zeitschr.  f.  phys.  Chem.  1 1 : Hft.  5. 
1887. 

uEidam  E.  Ueber  Pilzenentwickelung  in  den  Wurzeln  der 
Orchidaceen.  Jahresber.  d.  schles.  Ges.  f.  vaterl. 
Cultur.  57:297.  1879. 

•'Emmerling  A.  Untersuchungen  uber  die  Stickstoffernahrung 
der  Pflanzen.  Mitt.  a.  d.  Lab.  d.  Versuch.  Sta.  i.  Kiel. 
Hft.  1.  1879. 


196 


MINNESOTA  BOTANICAL  STUDIES. 


Emmerling  A.  Studien  tiber  die  Eiweissbildung  in  der  Pflanze. 
Landw.  Vers.  Sta.  Abh.  1.  1879. 

< Eriksson  J.  Studier  5fver  Luguminosernas  rfttknoler.  Doc- 
tordiss.  Lund.  1874. 

Also,  Acta  Univ.  Lund.  10.  1873. 

Far  low.  Tubercles  on  Leguminous  Roots.  Garden  and  For- 
est 1 : 135.  1888. 

v Fink  K.  Die  Mikroorganismen  in  der  Ackerkrume.  Fuhling’s 
Landw.  Ztg.  43:48,  853.  1893. 

Fitz  A.  Stickstoffquellefur  Mucor.  Deut.  Chem.  Rev.  8: 1540. 
1876. 

v Fisch  Rees,  und  Untersuchungen  fiber  den  Bau  und  Lebens- 
geschichte  der  Hirschtruffel-Elaphomyces.  Biblioth. 
Bot.  Hft.  7.1.  1887. 

Frank.  Ueber  die  biologische  Verhaltnisse  des  Thallus 
einiger  Krustenflechten.  Cohn’s  Beitr.  z.  Biol,  d 
Pflanzen.  2:123.  1876. 

Frank.  Ueber  die  Parasiten  in  den  Wurzelanschwellungen 
der  Leguminosen.  Bot.  Ztg.  37:377,  393.  1879. 

Frank.  Handbuch  der  Pflanzenkrankheiten.  131,  647,  674, 
748.  1880. 

Frank.  Ueber  die  auf  W urzelsymbiose  beruhende  Ernahrung 
gewisser  Baume  durch  unterirdische  Pilze.  Ber.  d, 
deut.  Bot.  Ges.  3:  128.  1885. 

Frank.  Neue  Mittheilungen  fiber  die  Mycorhiza  der  Baume 
und  der  Monotropa  hypopitys.  Ber.  d.  deut.  Bot. 
Ges.  3: . 1885. 

Frank.  Mikroorganismen  des  Erdbodens  Ber,  d.  deut.  Bot. 
Ges.  4:  Hft.  8.  1886. 

Frank.  Ueber  die  Quellung  der  Stickstoffnahrung  der 
Pflanzen.  Ber.  d.  deut.  Bot.  Ges.  4:293.  1886. 

Frank.  Sind  die  Wurzelanschwellungen  der  Erlen  und  Elae- 
agnaceen  Pilzgallen?  Ber.  d.  deut.  Bot.  Ges.  5:50. 

1887. 

Frank.  Ueber  neue  Mykorhiza  Formen.  Ber.  d.  deut.  Bot. 
Ges.  5:395.  1887. 

j^Frank.  Ursprung  und  Schicksal  der  Saltpetersaure  in  der 
Pflanze.  Ber.  d.  deut.  Bot.  Ges.  5.472.  1887. 

Frank.  Ernahrung  der  Pflanzen  mit  Stickstoff,  und  uebey  den 
Kreislauf  desselben  in  der  LandwirtschaTt.  Sep. 

1888.  Berlin. 


/Frank. 

Frank. 

Frank. 

Frank. 

Frank. 

Frank. 

'Frank. 

Frank. 

Frank. 

Frank 

■ Frank 

Frank. 

Frank. 

Frank. 

Frank. 

Frank. 

^rank. 


Mac  Dougal:  fixation  of  free  nitrogen.  197 

Ueber  den  Einfluss  welche  das  Sterilisiren  des  Erd- 
boden  anf  die  Pflanzenentwickelung  auslibt.  Ber.  d. 
deut.  Bot.  Ges.  6: — . 1888. 

Ueber  die  physiologische  Bedeutung  der  Mycorhiza. 
Ber.  d.  dent.  Bot.  Ges.  6:248.  1888. 

Untersuchungen  tjber  die  Ernahrung  der  Pflanze  mit 
Stickstoff.  Landw.  Jabrb.  18:419,  496.  1888.  - 
Was  niitzen  den  Waldbaumen  die  Wurzelpilze.  Forst. 
Bl.  Jan.  1.  1889. 

Ueber  den  Experimental  Nachweis  der  Assimilation 
freien  Stickstoffs  durch  erdboden*  bewahnenden  Algen. 
Ber.  d.  deut.  Bot.  Ges.  7 : 34.  1889. 

Ueber  die  gegenwartige  Stamm  unserer  Kenntnisse 
der  Assimilation  elementaren  Stickstoffs  durch  die 
Pflanze.  Ber.  d.  deut.  Bot.  Ges.  7 : 234.  1889. 

Pilzsymbiose  der  Leguminosen.  Sep.  1890.  Berlin. 
Pflanzeq.physiologie,  120.  1890.  Berlin. 

Ueber  Assimilation  von  Stickstoff  aus  Luft  durch 
Robinia  Pseudacacia.  Ber.  d.  deut.  Bot.  Ges.  8:292. 
1890. 

und  Otto.  Untersuchungen  uber  Stickstoffsassimila- 
tion  in  der  Pflanze.  Ber.  d.  deut.  Bot.  Ges.  8:331. 

1890. 

und  Otto.  Untersuchungen  liber  Stickstoflassimila- 
tion  in  der  Pflanze.  Naturw.  Wochen  Schr.  6:215. 

1891. 

Neue  Stimmen  liber  die  Stickstoflfrage.  Deut.  Landw. 
Presse,  21:119.  1894. 

Inwieweit  ist  der  freie  Luft-Stickstoff  flir  den  Er- 
nahrung der  Pflanzen  verwerthbar  ? Deut.  Landw. 
Presse,  18:779.  1891. 

Ueber  einege  neue  Versuche  betreffs  der  Stickstoffs- 
assimilation  in  der  Pflanze.  Deut.  Landw.  Presse. 
18:403.  1891. 

Ueber  die  auf  Verdauung  von  Pilze  abzielende  Sym- 
biose  der  mit  endotropic  Mykorhizen  begabten  Pflan- 
zen sowie,  der  Leguminosen  und  Erlen.  Ber.  d.  deut. 
Bot.  Ges.  9:244.  1891. 

Ueber  die  auf  den  Gasaustausch  beziiglichen  Einrich- 
tungen  und  Thatigkeiten  der  WurzelknOllchen  der 
Leguminosen.  Ber.  d.  deut.  Bot.  Ges.  10:271.  1892. 
Lehrbuch  der  Botanik  1 : 574.  1892. 


198 


MINNESOTA  BOTANICAL  STUDIES. 


Frank.  Die  Assimilation  freien  Stickstoifs  bei  den  Pfanzen 
in  ihrer  Abhangigkeit  von  Species,  von  Ernharungs- 
Verhaltnissen  und  von  Bodenarten.  Landw.  Jahrb.  21: 
Hft.  1 and  2.  1892. 

Frank.  Noch  ein  Wort  zur  Stickstoff-Frage.  Deut.  Landw. 
Presse,  20:183.  1893. 

Frank.  Die  Assimilation  des  freien  Stickstoffs  durch  die 
Pflanzenwelt.  Bot.  Ztg.  51:  Abth  1.  138.  1893. 

Frank.  Sur  l’importance  des  Mycorhizes  dans  la  nutrition 
des  plantes  humicoles.  Rev.  Eaux  et  Forets  38: 122. 
1894. 

Frank.  Die  Bedeutung  der  Mycorhiza  die  gemeine  Kiefer. 
Forstwiss.  Centralb.  April.  1894. 
v Frankland  E.  Chemical  changes  in  their  relations  to  Micro- 
organisms. Rep.  Brit.  A.  A.  S.  681.  1884. 

Frankland  P.  and  0.  C.  The  nitrifying  process  and  its  spe- 
cific ferment.  Proc.  Roy.  Soc.  Lond.  47:296.  1890. 

Phil.  Trans.  Roy.  Soc.  181:107.  1891. 

Frankland  P.  Micro-organisms  in  their  relation  to  chemi- 
cal change.  Nature  46: 135.  1892. 

Fries  E.  Sclerotium.  Systema  Mycologicae  2 : 250.  1823. 

Fries  Th.  M.  Om  Vaxtbolag.  Sartryck  ur  Svensk  Tidskrift. 
1892. 

Fromberg  P.  F.  H.  On  the  source  of  carbon  and  nitrogen  in 
plants  as  derived  from  the  soil.  Jour.  Ag.  2 : 41.  1847. 

Gain.  Influence  de  l’humidite  sur  le  development  des  nodosites 
des  Leguminosae.  Compt.  rend.  116: 1394.  1893. 

Gasparini  G.  Osservazioni  sulla  struttura  dei  spongiolari 
di  alcune  piante  leguminose.  Lette  all.  Ac.  di. 
Napolli.  1851. 

v Gasparini  G.  Richercha  sulla  natura  dei  succiatoria  la 
escrezione  delle  radici.  1856. 

Gantier  et  Drouin.  Recherches  sur  la  fixation  de  l’azote  par 
le  sol  et  les  vegetaux.  Compt.  rend.  106:  754,  863, 
944,  1098,  1174,  1232,  1460,  1605.  1888. 

i Gautier  und  Drouin.  Fixirung  von  Stickstoff  durch  den 
Boden  und  die  Gewasser.  Chem.  Centralb.  1 : No.  8. 
1892. 

Gautier  et  Drouin.  Remarques  sur  le  mecanisme  de  la  fixa- 
tion de  l’azote  par  le  sol  et  les  vegetaux.  Compt, 
rend.  114:19.  1892. 


Mac  Dougal:  fixation  of  free  nitrogen. 


199 


vGautier  und  Drouin.  Fixirung  des  atmosphareschen  Stick- 
stofies  durch  Boden  and  Pflanze.  Chem.  Centralb.  1 : 
No.  11.  1892. 

, Gibelli  G.  La  malattia  del  castagno,  ozzervazioni  esperiene. 
1879. 

Gibelli  G.  Nouvelles  etudes  sur  la  maladie  du  Chataignier 
dite  maladie  de  l’encre.  Arch.  d.  Biol.  Ital.  3 : 122. 
Gibelli  G.  Nuova  studi  sulla  malattia  del  castagno  detta  dell’ 
inchiostro.  1883.  Bologna. 

^Gilbert.  See  Laws. 

- Gilbert . Einige  neue  Ergebnisse  betr.  d.  Stickstoff  Quelle  d. 

Pflanze.  Chem.  Centralb.  No.  46.  3886. 

Godlewski  E.  Zur  Kenntniss  der  Nitrification.  Anzeig.  Akad. 
Wiss.  in  Krakau.  1892. 

Goebel  K.  Ueber  Prothallium  und  Keimpflanzen  von  Lycopo- 
dium inundatum.  Bot.  Ztg.  45: 161.  1887. 

v Goebel  K.  Zur  Keimungsgeschichte  der  Fame.  Ann.  d.  Jard. 
Bot.  d.  Buitenzorg.  7 : 74.  1888. 

Goebel  K.  Morphologische  und  Biologische  Studien.  4.  Ueber 
Javanische  Lebermoose.  Ann.  d.  Jardin.  Bot.  d.  Bui- 
tenzorg 9:6.  1891. 

Gottsche  C.  M.  Anatomischphysiologische  Untersuchungen 
iiber  Haplomitrium  Hookeri.  Verh.  d.  kais.  Leop. 
Car.  Akad.  d.  Naturf.  12:  Abth.  1.  265.  1843. 

^Gottsche  C.  M.  Ueber  das  Genus  Monoclea.  Bot.  Ztg.  15:281. 
1857. 

tGottsche  C.  M.  Uebersicht  und  kritische  Wurdigung  der  seit 
dem  Erscheinen  der  Synopsis  Hepoticorum  bekannt 
gewordenen  Leistrungen  in  der  Hepoticologie.  Bot. 
Ztg.  Beilage  16:140.  1858. 

^Gratiolet  et  Cloez.  Recherches  experimentales  sur  la  vegeta- 
tion des  plantes,  submergees.  Ann.  d.  Chim.  et  Phys. 
32:41.  1851. 

Gratiolet  et  Cloez.  Recherches  experimentales  sur  la  vege- 
tation des  plantes  submergees.  Jour.  f.  Prakt.  Chem. 
52:275.  1851,  and  53:  181.  1851. 

v^Gravis  A.  Observationes  anatomiques  sur  les  excroissances 
des  racines  de  l’aume.  Bull.  d.  1.  Soc.  d.  Bot.  d. 
Belgique.  18:  Pt.  1.  50.  1879. 

Gravis  A.  Note  sur  les  excroissances  des  racines  de  l’aune. 
Compt.  rend.  d.  1.  seance  men.  d.  1.  Soc.  roy.  d.  bot. 
Belgique.  1880. 


200 


MINNESOTA  BOTANICAL  STUDIES. 


Gregory  E.  Notes  on  some  botanical  reading  done  in  the 
laboratory  of  Professor  Schwendener  in  Berlin,  in 
June  and  July,  1889.  Bull.  Torr.  Bot.  Club  16:297. 
1889. 

Grosglik  S.  Die  Mycorhiza.  Wszechswiat  4:725.  1885. 

Warschau. 

Halsted  B.  D.  Nitrogen  assimilation  in  clover:  A hint.  Bull. 

Bot.  Dept.  A g.  Coll.  Iowa.  Feb.,  1888. 

Hariot  P.  Sur  une  Algue  qui  vit  dans  les  racine  d.  Cycad. 
Compt.  rend.  115:325.  1892. 

Hartig  R.  Ueber  die  symbiotische  Erscheinungen  im  Pflan- 
t zenleben.  Bot.  Centralb.  25:350.  1886. 

Hartig  R.  Die  pllanzliche  Wurzelparasiten.  Allg.  Forst.  u. 
Jagdztg.  April.  118.  1888. 

Hartig  R.  Die  pllanzliche  Wurzelparasiten.  Centralb.  f.  Bakt. 

u.  Par.-kunde.  3:1,  19,  58,  91,  118.  1888. 

Hartig  R.  Lehrbuch  der  Anatomie  und  Physiologie  der 
Pllanzen.  1891. 

Hartig  R.  Lehrbuch  der  Baumkrankheiten.  2Ed.  1889. 
Hartig  Th.  Jahresberichte  liber  die  Fortschritte  der  Forst- 
wissenschaft  und  forstliche  Naturkunde.  1837. 
Hartig  Th.  Vollstahdige  Naturgeschichte  der  Forstlichen 
Kultur-Pflanzen.  365.  1851. 

Hartig  Th.  Luft-Boden  und  Pflanzenkunde  in  ihrer  Anwen- 
dung  auf  Forstwissenschaft  (und  Gartenbau).  Lehr- 
* buch  der  Forster.  8th  Ed.  1 : 1840.  9th  Ed.  1851.  11th 
Ed.  1877. 

Hartig  Th.  Ueber  das  sogenannten  Absterben  der  Haarwur- 
zeln  (racines  chevelues  Duham. ) Bot.  Ztg.  2 1 : 289.  1863. 
Hartig  Th.  Anatomie  und  Physiologie  der  Holzpflanzen. 
1878. 

Harting  P.  und  Gunning.  Onderzoekingen  over  de  bron  der 
Stickstoff  voor  de  Planten  en  het  ammoniak  gehalte 
der  damp-kringslucht.  Amsterdam  Yerslag.  Akad. 
3:38.  1855. 

Harting  P.  Tegenbedenkingen  op  het  betoog  von  der  Herr 
G.  J.  Mulder  van  Waar  pekomen  de  niet  bemesten 
Planten  hare  Stickstoff  ? Amsterdam  Verslag.  Akad. 
3:89.  1855. 

^Harting  P.  Recherches  concernant  l’assimilation  de  l’azote 
de  l’air  par  les  vegetaux.  Compt.  rend.  41:  924.  1855. 
Harz  C.  0.  Ueber  vergleichende  Stickstoffdtingungsversuche. 
Bot.  Centralb.  33:218.  1888. 


Mac  Dougal:  fixation  of  free  nitrogen.  201 

Heiden  E.  Ueber  das  Absorptions- VermOgen  des  Bodens  und 
die  Aufnahme  der  Pflanzen  Nahrstoffe  in  der  Pflanze. 
Ann.  Landw.  41:111,  227,  343.  1863. 

Hellriegel  and  Wilfarth.  Absorption  of  nitrogen  by  plants. 
Bied.  Centralb.  228.  1888. 

^ Hellriegel.  Welche  Stickstoff  Quellen  stehen  den  Pflanzen  zu 
Gebote?  Tageblatt  d.  Naturforscher  Versamml.  z. 
Berlin  290.  1886. 

Hellriegel  und  Wilfarth.  Untersnchungen  nber  die  Stickstoff-  , 
nahrung  der  Gramineen  nnd  Leguminoseen.  1888. 
Berlin. 

Hellriegel.  Ueber  die  Beziehungen  der  Bakterien  zu  der  Stick- 
stoffernahrung  der  Leguminosen.  Zeitschr.  f.  d.  Ver. 
f.  Rubenzucker  Industrie  d.  deut.  Reiches.  241.  1886. 

Also,  Nov.  1888. 

v Hellriegel.  Ueber  die  Sticks  toll  nahrung  landwirtschaftliche 
Cultur  gewachse.  Bericht.  Wien.  1890. 

✓^Hellriegel  und  Wilfarth.  Erfolgt  die  Assimilation  des  freien 
Stickstoffs  durch  die  Leguminosen  unter  Mitwirkung 
niederer  Organismen  ? Ber.  d.  deut.  Bot.  Ges.  7 : 138. 
1889. 

^Hellriegel  H.  Bemerkungen  zu  dem  Aufsatze  von  B.  Frank 
“Ueber  den  Einfluss  welchen  das  Sterilisiren  der  Erd- 
bodens  auf  die  Pflanzenentwickelung  austtbt.”  Ber.  d. 
deut.  Bot.  Ges.  7 : 131.  1889. 

1 Henschel  G.  1st  die  zu  Mycorhizabildungen  fuhrende  Sym- 
biose  an  j ungen  Fichtenpflanzen  schadlich  ? Oest. 
Vierteljahrschr.  f.  Forstwesen.  113.  1887. 

Hiltner.  See  Nobbe,  Schmid  and  Hotter. 

Hoffman  H.  Ueber  Bacterien.  Bot.  Ztg.  27:265.  1869. 

Hofmeister  W.  Allgemeine  Morphologie  der  Gewachse.  1868. 
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202 


MINNESOTA  BOTANICAL  STUDIES. 


Jager  G.  Ueber  eine  krankhafte  Veranderung  der  Bluthen 
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Janczewski  E.  Y.  Das  Spitzenwachstnm  der  Phanerogamen 
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* Jokow  F.  Die  chlorophyllfreien  Humus  pflanzen  nachi  hren 
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Jonnson.  Studier  bfver  algaparasitism  hos  Gunnera  L. 
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Joergensen  A.  Bidrag  til  Rodens  Naturhistorie.  Bot.  Tidsskr. 
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Joergensen  A.  Korkdanelsen  paa  Roden.  Bot.  Tidsskr.  11: 
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Jumelle  H.  Recherches  physiologiques  sur  les  Lichens.  Rev. 

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Kamienski  Fr.  Les  organs  vegetatifs  du  Monotropa  hypopi- 
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Mac  Dougal:  fixation  of  free  nitrogen.  203 

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; Kny  L.  Zu  dem  Aufsatze  des  Herrn  Prof.  B.  Frank  “Ueber 
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K&ock  A.  Zur  Kenntniss  der  Faden  in  den  Wurzelknollchen 
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Kossowitsch  P.  Untersuehungen  ueber  die  Frage  ob  die 
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i-Xuhn  Y.  R.  Untersuehungen  uber  die  Anatomie  der  Marattia 
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Lachmann  J.  Ueber  KnQllchen  der  Leguminosen.  Landw 
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204 


MINNESOTA  BOTANICAL  STUDIES. 


Lachmann  J.  Knollen  an  den  Wnrzeln  der  Leguminosem 
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Laurent  E.  Sur  le  microbe  des  nodosites  des  Legumineuses. 
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-Laurent  E.  Experiences  sur  la  reduction  des  nitrates  par  les 
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Laurent.  See  Schloesing. 

>Lawes  and  Gilbert.  On  the  present  position  of  the  question  of 
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^Lawes  and  Gilbert.  On  the  sources  of  the  nitrogen  of  vegeta- 
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^Lawes  and  Gilbert.  Assimilation  of  nitrogen  by  plants.  Journ. 
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Mac  Dougal:  fixation  of  free  nitrogen.  205 

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Leplay  H.  Sur  la  formation  des  acides  organiques,  des 
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206 


MINNESOTA  BOTANICAL  STUDIES. 


Loew  0.  Ueber  die  Ernahrungsweise  des  nitrificirenden  Spalt- 
pilzes  Nitromonas.  Bot.  Centraib.  46:222.  1891. 

Loew  0.  “Nitrification  by  a Schizomycete.”  Bot.  Ver.  Mun- 
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Loew  0.  The  synthetical  powers  of  micro-organisms,  Science 
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Lonay  A.  La  question  de  l’azote  et  culture  les  Legumineuses, 
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Lotsy  J.  P.  A contribution  to  the  investigation  of  the  assim- 
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Lotsy  J.  P.  On  the  assimilation  of  free  nitrogen  by  plants. 

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Lundstroem  A.  N.  Om  mycodomatier  pa  papilionaoernads 
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Lundstroem  A.  N.  Ueber  symbiotische  Bildungen  bei  den 
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Lundstroem  A.  N.  Ueber  Mycodomatien  in  den  Wurzeln  der 
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Also  Naturv.  Studentsallsk.  April  28,  1887.  Upsala. 

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^Magnanimi,  Leon  und,  Nitrification  des  organischen  Stick- 
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Mac  Dougal:  FIXATION  OF  FREE  NITROGEN.  207 

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Meyen  J.  Ueber  das  Hervorwachsen  parasitischer  Gebilde 
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JMeyer  A.  Ueber  die  Knollen  der  einheimischen  Orchideen. 
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208 


MINNESOTA  BOTANICAL  STUDIES. 


Miles.  Die  nitrifizirenden  Mikrpben,  Chem.  Centralb.  No 
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Miles.  Biological  factors  in  the  nutrition  of  farm  crops.  Proc. 
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Millon  E.  Nitrification.  Chem.  News  2:  No.  56.  263,  337.  1860. 

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Millon  E.  Theorie  chimique  de  la  nitrification.  Jour.  d.  Pharm. 
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^Millon  E.  Theorie  chimique  de  la  nitrification.  Chem.  News 
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Millon  E.  Nitrification.  Chem.  News.  82.  1864. 

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Moeller  H.  Beitrag  zur  Kenntniss  der  Frankia  subtilis. 
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■"Moeller  A.  Ueber  die  Cultur  fiechtenbildener  Ascomyceten 
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L Morren  C.  Experiences  sur  l’absorption  de  l’azote  par  les  ani- 
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Mulder  G.  H,  Ueber  die  condensation  des  Stickstoffs  aus  der 
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Mac  Dougal:  fixation  of  free  nitrogen. 


209 


Mulder  G,  H,  Ueber  die  Quelle  des  Sticks  toffs  in  den  Pflanzen . 
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Mulder  G.  H.  Van  Waar  bekommen  die  niet  b ernes  te  plan  ten 
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Mulder  G,  H,  Versuch  einer  Phys.  Chem.  751. 

Muller  P,  E,  Bemerkungen  ueber  die  Mycorhiza  der  Buche. 

Bot.  Centralb.  2 6 : 22.  1886. 

Muntz,  See  Schloesing. 

Muntz  A.  De  quelques  faits  d’  oxydation  et  de  reduction, 
produits  par  les  organismes  microsc.  du  sol.  Journ.  d. 
Pharm.  et  d.  Chem.  5 Ser.  12:  No.  6.  1885. 

Muntz  and  Marcano.  Sur  la  formation  des  terres  nitrees  dans 
les  regions  tropicales.  Journ.  d.  Pharm.  et  d.  Chem.  5 
Ser.  12:  No.  6.  1885. 

Muntz  A.  Ueber  einige  Oxidation  und  Reduction  durch  Mik- 
roorganismen  im  Boden.  Chem.  Centralb.  No.  37. 
1885. 

Muntz  A.  Ueber  d.  Bildung  d.  saltpeterhaltigen  Erden  in  den 
Tropen.  Chem.  Centralb.  No.  37.  1885. 

Muntz  A.  Sur  la  decomposition  des  engrais  organiques  dans 
le  sol.  Compt.  rend.  110:1206.  1890. 

Muntz  A.  Sur  la  decomposition  des  engrais  organiques  dans 
le  sol.  Compt.  rend.  110: 1026.  1890. 

Muntz  A.  Du  role  des  engrais  verts  comme  furnures  azote^s. 
Compt.  rend.  110:972.  1890. 

Muntz  A.  Sur  la  formation  des  nitrates  dans  la  terre.  Compt. 
rend.  112:1142.  1891. 

Muntz  A.  Sur  la  formation  des  nitrates  dans  la  terre.  Compt. 
rend.  112:1143.  1891. 

-Muntz  and  Coudon.  La  fermentation  ammoniacale  de  la  terre. 
Ann.  Agron.  1 9 : 209.  1893. 

'-N.  H.  J.  M.  The  fixation  of  free  nitrogen.  Nature,  24:41. 
1890. 

-Naegeli.  Botanische  Beitrage:  Pilze  im  Innern  von  Zellen 
Linnaea  16:278.  1842. 

"Naegeli.  Ernahrungsmechanismus  der  niederen  Organismen. 

Sitzber.  d.  Munch.  Akad.  July,  1879. 
uNaegeli.  Ernahrung  der  niederer  Pilze  durch  Kohlen  und 
Stickstoffverbindungen.  Bot.  Mittheil.  3 : 395.  1881. 

"Nathusius.  Symbiose  der  Waldbiiume  mit  Mycorhiza.  Zeit- 
schr.  f.  Naturw.  62:Hft.  6 1890. 

'-Nicolai.  Das  Wachstum  der  Wurzel.  Schr.  d.  phys.-Okon. 
Ges.  z.  Koenigsberg.  7 : 35,  78.  1875. 


210  MINNESOTA  BOTANICAL  STUDIES. 

Noack  F.  Ueber  Micorhizende-bildende  Pilze.  Bot.  Ztg. 
47:389.  1889. 

Nobbe  F.  Vegetationsversuche  in  Boden  mit  lokalisirten 
Nathrstoffen.  Landw.  Ver.  Sta.  6:98.  1868. 

iNobbe  F.  Ueber  die  Stickstoffernahrung  der  Leguminosen. 

Verhandl.  d.  Ges.  Deut.  Naturf.  nnd  Aerzte.  Ver- 
samml  z.  Bremen,  2:551.  1890. 

-Nobbe  F.  Stiekstoffernabrung  der  Leguminosen.  Chem.  Cen- 
tralb.  1:  No.  6.  1891. 

i Nobbe,  Schmid^  Hiltner  and  Hotter.  Versuche  ueber  die  Stick- 
stoff assimilation  der  Leguminosen.  Landw.  Yer.  Sta. 
39:327.  1891 

Nobbe,  Schmid^  Hiltner  and  Hotter.  Ueber  die  physiologische 
Bedeutung  den  WurzelknGllchen  von  Eleagnus  angus- 
tifolius.  Landw.  Ver.  Sta.  41 : 138.  1892. 

INobbe^  Schmid,  Hiltner  and  Hotter.  Ueber  die  Verbreitungs- 
^ fahigkeit  der  Leguminosen  Bacterien  im  Boden. 
Landw.  Ver.  Sta.  41:137.  1892. 

Nobbe  and  Hiltner.  “The  interchange  between  leguminous 
plants  and  the  bacteria  causing  root  tubercles.” 
Sachss.  Landw.  Zeitschr.  165.  1893. 

^Oliver  F.  W.  On  Sarcodes  sanguinea.  Ann.  Bot.  4:303. 
1890. 

-Otto  R.  Die  Assimalation  des  freien  atmospharischen  Stick- 
stoffes  durch  die  Pflanze.  Bot.  Centralb.  46:387. 
1890.  Also,  47:62,  123,  175.  1891. 

Otto.  See  Prank. 

dPenzig  0.  Die  Krankheit  der  Edelkastanien  und  B.  Frank’s 
Mykorhiza.  Ber.  d.  deut.  Bot.  Ges.  3 : 301.  1885. 

^Persoon.  Traite  sur  les  champignons  comestibles.  1818. 
Petermann  A.  “Contribution  a la  question  de  l’azote.”  Mem. 

d.  1’  Acad.  Roy.  d.  Belg.  1891. 

Petermann  A.  Beitrage  zur  Stickstoffrage.  Abstract.  Chem. 
Centralb.  1:988.  1893.  Ibid.  2:889.  1892.  Ibid. 

3:  No.  20.  1892. 

-Petermann  A.  Contribution  a la  question  de  l’azote.  Mem.  d. 

T Acad.  roy.  d.  Belg.  47.  1892. 

<Petermann  A.  Contribution  a la  question  de  1’azote.  Bull. 

Acad,  Roy.  Belg.  3,  Ser.  25:267.  1893. 

- Pfeifer  W.  Ueber  Fleischfressende  Pflanzen  und  ueber  die 
Ernahrung  durch  Aufnahme  organischer  Stickstoff 
ueberhaupt.  Landw.  Jahrb.  6:969.  1877. 

Pfeifer  W.  Pllanzenphysiologie  1 : 239.  1880. 


Mac  Dougal:  fixation  of  free  nitrogen. 


211 


^Pfeiffer  A.  Die  Beziehungen  der  Boden  Capillaritat  zum 
Transport  von  Bacterien.  Zeitschrf.  Hyg,  1:394.  1886. 

1 Pfeiffer  A.  Antwort  anf  die  Entgegnnng  des  Herrn  Dr.  Soyka, 
etc.  Zeitschr.  f.  Hyg.  2:239.  1887. 

~ Pfeil  W.  Wunschenwerthe  Abbildung  der  Baumwurzeln  wie 
sie  sich  nach  dem  Alter  des  Baumes  in  verschiedenen 
Boden- andern.  Krit.  Bl.  f.  Eorst.  n.  Jagdwiss.  25:255. 


JPfeil  W.  Recension  von  Schacht’s  “Beitrage  zur  Anatomie 
und  Physiologie  der  Gewachse.”  Krit.  Bl.  f.  Forst.  u. 
Jagdwiss.  35:51.  1855. 

Pichard  P.  Influence  dans  les  terres  neues  des  propor- 
tions d’argile  et  d’azote  organique  sur  la  fixation 
d’azote  atmospherique,  sur  la  conservation  de  l’azote 
et  sur  la  nitrification.  Comp t.  rend.  114:  81.  1892. 

Pichi.  Alcuue  osservazione  sui  tubercoli  radicali  delle  Leg- 
uminose.  Atti  della  Soc.  Tosc.  di  Sc.  nat.  1888. 

-Pott.  Untersuchungen  iiber  Wachstumisverhaltnisse  der  Leg- 
uminoseen.  Landwirtsch.  Versuchssta.  25:Hft.  1 

and  2. 

''Poulsen  Y.  A.  Bidrag  til  Triuridaceernes.  1886. 

wPoulsen  Y.  A.  Triuris  major  n.  sp.  Et  Bidrag  til  Triurida- 
ceernes Naturhistorie.  Bot.  Tiddskr.  17:293.  1890. 

■'Prantl  K.  Untersuchungen  ueber  die  Regeneration  des  Veg- 
etationspunktes  an  Angiospermwurzeln.  Arbeitld. 
bot.  Inst.  z.  Wurzburg.  1:546.  1874. 

Prantl  K.  Die  Assimilation  freien  Stickstoff  und  der  Parasitis- 
mus  von  Nostoc.  Hedw.  28: 135.  1889. 

vPrazmowski.  Ueber  die  WurzelknQllchen  der  Leguminosen. 
Bot.  Cent  ralb.  36: 215,  248,  280.  1888. 

Prazmowski.  Das  Wesen  und  die  biologische  Bedeutung  der 
WurzelknQllchen  der  Erbse.  Ber.  a.  d.  Sitz.  d.  Akad.  i. 
Krakau.  1889. 

Prazmowski.  Die  Wurzelknollchen  der  Erbse.  die  Aetiologie 
und  Entwickelungsgeschichte  der  KnQllchen.  Landw. 
Vers.  Sta.  37:Hft.  3 and  4,  104,  161.  1890.  See  also 

38 : Hft.  5.  1890. 

Prillieux  E.  De  la  structure  anatomique  et  du  mode  de  veg- 
etation du  Neottia  nidus,  avis.  Ann.  d.  Sc.  Nat.  Bot. 
4Ser.  5:267.  1856. 

Prillieux  E.  Sur  la  nature  et  la  cause  de  la  formation  des 
tubercles  qui  nassent  sur  les  racines  des  LeguminQuses. 
Bull.  Soc.  Bot.  d.  Prance.  26:98.  1879. 


1848. 


212 


MINNESOTA  BOTANICAL  STUDIES. 


Prillieux  E.  Anciennes  observations  sur  les  tubercles  des 
racines  des  Legumineuses.  Compt.  rend.  111:926. 
1890. 

Prillieux  E.  Anciennes  observations  sur  les  tubercules  des 
racines  des  Legumineuses.  Bull.  d.  1.  Soc.  Bot.  d. 
France.  13:  No.  1.  1891. 

Prove.  Untersuchungen  ueber  die  S ticks  toff  nahrung  der  Erb- 
sen.  Zeitschr.  Landw.  Ver.  Bayern.  82:85.  1892. 

Pugh,  Lawes  and  Gilbert.  Assimilation  of  nitrogen  by  plants. 
Rep.  Brit.  A.  A.  S.  51.  1852. 

Rabuteau.  Recherches  sur  les  metamorphoses  et  1’  elimina- 
tion des  azotites.  Compt.  rend.  Soc.  d.  Biol.  5 Ser. 
1:66.  1870. 

Raulin.  Etudes  chimiques  sur  la  vegetation  des  Musedinees. 
Compt.  rend.  57:229.  1863. 

Rees  M.  Entstehung  der  Flechte-Collema  glaucescens.  Mon- 
atsber.  d.  Berl.  Akad.  Oct.  1871. 

LRees  M.  Ueber  den  Parasitismus  von  Elaphomyces  granu- 
latus.  Sitzungs-Ber.  der  Physik.-Med.  Soc.  z.  Er- 
langen. May.  1880. 

Rees  M.  Ueber  Elaphomyces  und  sonstige  Wurzelpilze.  Ber. 
d.  deut.  Bot.  Ges.  3:293.  1885. 

Rees  und  Fisch.  Untersuchungen  ueber  den  Bau  und  Lebens- 
geschichte  der  Hirschtrutfel- Elaphomyces.  Biblioth. 
Bot.  Hft.  7:1.  1887. 

Reinke  J.  Ueber  gonidienartige  Bildungen  in  einer  dicoty- 
lischer  Pflanze.  Nach.  v.  d.  konigl.  Ges.  d.  Wiss.  u. 
Univ.  z.  Gottingen,  100.  1871,  1872. 

Reinke  J.  Andeutungen  ueber  den  bau  der  Wurzel  von  Pinus 
Pinea.  Bot.  Ztg.  30:49.  1872. 

Reinke  J.  Morphologische  Abhandlungen.  1873. 

-Reinke  J.  Zur  Kenntniss  der  Rhizome  von  Corallorhiza  und 
Epipogon.  Flora.  56:145,  161,  177.  1873. 

Reinke  J.  Zwei  parasitische  Algen.  Bot.  Ztg.  37 : 473.  1879. 

Reinsch  H.  Ueber  eigenthum  lichen  Stoff  in  der  Monotropa 
hypopitys.  Jahrb.  f.  prakt.  Pharm.  u.  verw.  Facher, 
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Reissek  S.  Endophyten  der  Pflanzenzelle.  1846.  Uren. 

- Resa  F.  Ueber  die  Periode  der  Wurzelbildung.  Inaug.  Diss. 
1877. 

Resa  F.  Untersuchungen  ueber  die  Periode  der  Wurzelbil- 
dung, insbesondere  bei  den  Holzgewachse.  Forstl.  Bl. 
321.  1878. 


Mac  Dougal:  fixation  of  free  nitrogen. 


213 


Jleum  J.  A,  Pflanzen-Physiologie.  1835. 
vReuss  R.  Per  Waldfeldbau  im  Dienste  des  Forstkulturbe- 
triebs.  Centralb.  f.  d.  gesamm.  Fortstw.  289,  354. 
1889. 

Rockwoodj  see  Atwater. 

Rossmassler.  Der  Wald.  418.  1863. 

<-Rostrop  E.  Sygdomme  hos  Skovtraeerne,  foraarsagede  af 
ikkernstatige  Snyltesvampe.  Tidsskr.  f.  Skovbrog. 
4:113.  1880. 

^Russel  H.  L.  The  fixation  of  free  nitrogen  by  plants  Bot. 


• 'Russo w.  Vergleichende  Untersuchungen  der  Leitbtindelkryp- 
togamen.  122.  1872.  St.  Petersburg. 

^Rylands  T.  G.  On  the  nature  of  the  byssoid  substance  found 
investing  the  roots  of  Monotropa  Hypopitys.  The 
Phytologist  1 :341.  1842. 

i-Sarauw  F.  L.  Ueber  die  Mykorhizen  unserer  Waldbaume.  Bot. 
Centralb.  53:343.  1893. 

* vSarauw  F.  L.  RMsymbiose  og  mykorhizer  saerlig  hos 
skovtraerne.  1893. 

-Sachs  J.  Zur  Entwickelungsgeschichte  d.  Collema  bulbosa. 
Bot.  Ztg.  13:1.  1855. 

“'Sachsse.  Keimung  von  Pisum  sativum.  1872. 

1 Serno.  Ueber  das  Auftreten  und  des  Verhalten  der  Salpeter- 
saure  in  den  Pflanze.  Landw.  Jahrb.  18:  877.  1889. 

^Schacht  H.  Physiologische  Botanik.  die  Pflanzenzelle.  1852. 

►-'Schacht  H.  Beitrag  zur  Entwickelungsgeschichte  der  Wur- 
zel.  Flora  36:261.  1853. 

Schacht  H.  Ueber  Pilzfaden  im  innern  der  Zellen  und  der 


Schacht  H.  Beitrag  zur  Anatomie  und  Physiologie  der  Ge- 
wachse.  160.  1854. 

"'  Schacht  H.  Lehrbuch  d.  Anatomie  und  Physiologie.  2 : 147. 
1859. 

‘■'Schacht  H.  Der  Baum  172.  1860. 

w Schenk.  Symbiose  einer  Ericaceae  und  Mycorhiza.  Zeitschr. 
f.  Naturw.  62:Hft.  6.  1890. 

HSchenk.  Ueber  Cycas  Wurzeln  mit  Algencolonien.  Tagebl.  d. 

45  Versamml.  deut.  Naturf.  u.  Aerzte  z.  Leipzig.  1872. 

• Schindler.  Ueber  die  biologische  Bedeutung  der  WurzelknOll- 
chen  bei  der  Papilionaceen.  Jour.  f.  Landw.  33:325. 


Gazette.  1 9 : 284.  1894. 


StarkemehlkSrner.  Ber.  u.  d.  Verh.  d.  konigl.  preuss. 
Akad.  d.  Wiss.  z.  Berlin.  377.  1854. 


1885. 


214 


MINNESOTA  BOTANICAL  STUDIES. 


dSchindler.  Ueber  die  Bedeutung  die  sogenannten  Wurzel- 
knftllchen  bei  der  Papilionaceen.  Oester.  Landw. 
Wochenb.  11:  No.  34.  1885. 

Schindler.  Zur  Kenntniss  der  Wurzelknftllchen  der  Papilion- 
aceen. Bot.  Centralb.  18:86.  1888. 

Schlechtendal.  Phaseolus  multiflorus.  Bot.  Ztg.  10:893. 
1852. 

Schleiden  M.  J.  Grundziige  der  wissenschaftliche  Botanik. 
1842-43.  1845-46.  1849-50. 

Schlicht  A.  Ueber  nene  Palle  von  Symbiose  der  Pflanzen- 
wtirzeln  mit  Pilzen.  Ber.  d.  deut.  Bot  Ges.  269.  1888. 

Schlicht  A.  Beitrag  zur  Kenntniss  der  Verbreitung  nnd  der 
Bedeutung  der  Mykorhizen.  Inaug.  Diss.  Univ.  Er- 
langen. 1889. 

Schloesing  and  Muntz.  Sur  la  nitrification  par  les  ferments 
organises.  Compt.  rend.  80:1250,  1873;  84:301,  1877; 
85:1018,  1878,  and  86:891,  1879. 

Schloesing  Th.  Sur  les  relations  de  l’azote  atmospherique 
avec  la  terre  vegetale.  Compt.  rend.  106:805,  898, 
982,  1123.  1888;  also  107:290.  1888. 

^Schloesing  Th.  Sur  la  nitrification  de  l’ammoniaque.  Compt. 
rend.  109:423,  883.  1889. 

^Schloesing  Th.  Sur  les  relations  de  l’azote  atmospherique 
avec  la  terre  vegetale.  Compt.  rend.  109:210,  345. 
1889. 

/Schloesing  and  Laurent.  Sur  la  fixation  de  l’azote  gazeux  par 
les  Legumineuses.  Compt.  rend.  111:750,  1800;  also 
115:659,  732,  1892. 

Schloesing  Th.  Remarques  au  sujet  des  observations  de  M. 
Berthelot,  etc.  Compt.  rend.  110:612.  1890. 

Schloesing  Th.  Sur  l’absorption  l’ammoniaque  de  l’atmos- 
phere  par  la  terre  vegetale.  Compt.  rend.  110:429, 
499.  1890. 

Schloesing  and  Laurent.  Sur  la  fixation  de  l’azote  libre  par 
les  plantes.  Compt.  rend.  113:  776.  1891. 

^Schloesing  Th.  Observations  sur  la  communication  de  M. 
Berthelot.  Compt.  rend.  115:636.  1892. 

Schloesing  and  Laurent.  Recherches  sur  la  fixation  de  l’azote 
libre  par  les  plantes.  Ann.  Inst.  Past.  6 : 65.  1892. 

Schmid.  See  Nobbe,  Hiltner  and  Hotter. 

Schmitt er.  “New  experiments  in  soil  inoculation.”  Woch- 
enschr.  5k5n.  Ges.  251.  1891. 


Mac  Dougal:  fixation  of  free  nitrogen. 


215 


Schmitz  Fr.  Phyllosiphon  Arisari.  Bot.  Ztg.  40:523,  539, 
566,  579.  1882. 

^Schneider  A.  Observations  on  some  American  Rhizobia. 
Bull.  Torr.  Bot.  Clnb  19:205.  1892. 

- Schneider  A.  Recent  investigations  concerning  rhizobia  and 

free  nitrogen  assimilation.  A g.  Science  7 : 549.  1893. 

'--Schneider  A.  A new  factor  in  Agriculture.  University  of  Illi- 
nois. Ag.  Ex.  Sta.  Bull.  No.  29,  December,  273.  1893. 
^Schneider  A.  Morphology  of  the  root  tubercles  of  the  Le- 
guminosae.  Am.  Naturalist  27 : 782.  1893. 

^ Schneider  A.  Beitrag  zur  Kenntniss  der  Rhizobien.  Ber.  d. 
deut.  Bot.  Ges.  12: 11.  1894. 

Solms-Laubach.  Der  Aufbau  des  Stockes  von  Psilotum  tri- 
quetrum und  dessen  Entwickelung  aus  der  Brutknospe. 
Ann.  d.  Jard.  Bot.  d.  Buitenzorg.  4:139.  1884. 
VSorauer  P.  Wurzelknollen.  Pflanzenkrankheiten  1 : 743. 
1886. 

^Sorauer  P.  Die  Hernie  der  Erlenwurzeln.  Pflanzenkrank- 
heiten 2:73.  1886. 

/Sorauer  P.  Zusammenstellung  der  neuern  Arbeiten  ueber  die 
WurzelknOllchen  und  deren  als  Bakterien  ausgespro- 
chene  InhaltskOrperchen.  Bot.  Centralb.  31:308,  343, 
1887. 

Schuetzler  J.  B.  Sur  les  germes  organises  de  la  nitrification. 

Bull.  Soc.  vand.  d.  Sc.  Nat.  Lausanne.  22:213.  1886. 

Schulze  E.  Ueber  die  Processe  durch  welche  in  der  Natur 
ein  freier  Stickstofl  in  Stickstoffverbindungen  tiberge- 
geftihrt  wird.  Landw.  Jahrb.  6:Hft.  4 and  5.  1877. 

w Schwarz  F.  Die  Wurzelhaare  der  Pflanzen.  Unters.  a.  b.  bot. 

Inst.  z.  Tub.  1 :Hft.  1,  135.  1883. 

*•  Schwendener  S.  Ueber  die  wahre  Natur  der  Flechten.  Verh. 

d.  schweiz.  naturf,  Ges.  z.  Rheinfelden.  Sept.  1867. 
-'Schwendener  S.  Untersuchungen  ueber  den  Flechtenthallus. 

Nachtrag  Nageli,  Beitrag  zur  wiss.  Bot.  4:195.  1868. 

- Schwendener  S.  Die  Algentypen  der  Flechtengonidien.  1869. 
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krankheiten.  1 : Abt.  2 Hft.  3.  1887. 

-Soyka  J.  Entgegnung  auf  Herrn  Dr.  A.  Pfleifler’s  Aufsatz 
“Die  Beziehungen  der  Boden  Capillaritat.  ” Zeitschr. 
f.  Hyg.  2:96.  1887. 

^Storer.  Agriculture,  1:33,309,  420,  467,  etc.  1892.  Boston. 
'-Tacke  B.  Ueber  die  Entwickelung  von  Stickstoff  bei  Faulniss. 
Landw.  Jahrb.  16:  917.  1887. 


216 


MINNESOTA  BOTANICAL  STUDIES. 


Tacke  B.  Ueber  den  Stickstoifverlust  bei  der  Nitrification  und 
den  Sticks  toff  gewinn  im  vegetations  freien  Erdboden. 
Landw.  Jahrb.  18: 439.  1889. 

Thomae  K.  Bildung  der  Eiweisskorper  in  der  Pflanze.  Na- 
turw.  Wochenschr.  8: 469.  1892. 

Thomas  M.  B.  The  Genus  Corallorhiza.  Bot.  Gazette  18:166. 
1892. 

Treviranus  L.  C.  Ueber  die  Neigung  der  Hulsengew&chse  zu 
unterirdischen  Knollenbildung.  Bot.  Ztg,  11:393. 
1853. 

Thumen  von.  Les  Mycorhizes  et  les  theories  nouvelles  de  la 
vie  complexe  biologie.  Rev.  gen.  d.  Sc.  Pures  et  Appl. 
1:326. 

Tieghem  P.  van.  Recherches  sur  la  symmetrie  de  la  structure 
des  plantes  vasculaires.  Ann.  d.  Sc.  Nat.  Bot.  5 Ser. 
13:5.  1871. 

Tieghem  P.  van.  Sur  le  reseau  de  soutien  de  l’ecorce  de  la 
racine.  Ann.  d.  Sc.  Nat.  Bot.  7 Ser.  7 : 375.  1888. 

Tieghem  van  and  Douliot.  Recherches  comparatives  sur  I’or- 
igine  des  membres  endogenes  dans  les  plantes  vascu- 
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Treub  M.  Korte  bot.  aanteekenimgen  II;  Nostoccolonien  in 
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Mac  Dougal:  fixation  of  free  nitrogen.  217 

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218 


MINNESOTA  BOTANICAL  STUDIES. 


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Mac  Dougal:  fixation  of  free  nitrogen. 


219 


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lW agner  P.  Einige  Zeit  und  Streitfragen  aus  dem  Gebiet  der 
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220 


MINNESOTA  BOTANICAL  STUDIES. 


Wigand.  Bacterien  innerhalb  der  geschlossenen  gewebes  der 
knollenartigen  anschwellungen  der  Papilionaceen- 
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Verhandl.  d.  Ges.  Deut.  Naturf.  und  Aerzte.  Ver- 
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Willfarth.  Stickstoffaufnahme  der  Plianzen.  Chem.  Centralb. 
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1893. 

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Mac  Dougal:  fixation  of  free  nitrogen. 


221 


^Wollny.  Ueber  die  Beziehungen  der  Mikroorganismen  zur 
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Woods  C.  D.  The  acquisition  of  nitrogen  by  growing  plants. 

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Woronin.  Observations  sur  certaines  excroissances  que  pre- 
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Ann.  d.  Sc.  Nat.  Bot.  5.  Ser.  7 : 73.  1867. 

Woronin.  Plasmodiophora  Brassicae.  Pringsheim’s  Jahrb. 
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‘^ortman.  Ueber  die  neuesten  Untersuchungen  beziigiich  der 
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l^Wydler  H.  Kleinere  Beitrage  zur  Kenntniss  einheimischer 
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^Zimmermann  und  Wolff.  Beitrag  zur  Chemieund  Physiologie 
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222 


MINNESOTA  BOTANICAL  STUDIES. 


Description  op  Plates. 

Plate  VII. 

The  Anderson  registering  balance  set  up  to  weigh  transpired  water. 

Plate  YIII. 

The  Frost  electric  auxanometer  in  use  to  determine  growth  in  length. 

Plate  IX. 

The  Frost  time-recorder. 

Plate  X. 

The  Frost  auxanometer  connected  with  recorder. 

From  photographs  by  Professor  Wm.  R.  Appleby, 


Bulletin  No.  9.  MINNESOTA  BOTANICAL  STUDIES.  Sept.  1894. 


I 


PLATE  VII 


I 


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Bulletin  No.  9.  MINNESOTA  BOTANICAL  STUDIES  Sept.  1894 


PLATE  VIII. 


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Bulletin  No.  9.  MINNESOTA  BOTANICAL  STUDIES.  Sept.  1894. 


PLATE  IX. 


1 


Bulletin  No.  9.  MINNESOTA  BOTANICAL  STUDIES.  Sept  1894. 


PLATE  X. 


1* 


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